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Research shows a clear benefit for CT lung-cancer screening among individuals who meet strict criteria. Patients and referrers should understand both the benefit and the potential for false positive results.

"Twenty percent fewer deaths were reported in the study group that underwent CT scanning of the chest versus the control group that did not," said Theresa McLoud, MD, associate radiologist-in-chief of the Mass General Department of Radiology. "This is a significant benefit, which has potential for our patients. But at the same time, it's important that we use this test wisely because the study applies only to a high-risk group."

Exam criteria

National medical societies such as the American Cancer Society are now developing guidelines for screening programs, but none are currently available. In the meantime, Mass General Imaging will be following the inclusion criteria used in the National Lung Cancer Screening Trial, which were as follows:

Individuals between the ages of 55 and 74 who are current or former smokers

History of at least 30 pack years of smoking (a pack year equals the number of packs smoked per day times the number of years smoked)

Patients should not have a history of any cancer within the past five years

Screening CTs will be available only on a self-pay basis. The total fee will is $350 payable at the time of the study. (If the study detects something, follow-up CT scans should be covered by the patient’s insurance, but as always patients are encouraged to confirm coverage with their insurance carrier.)

In accordance with Mass General Imaging’s commitment to reducing radiation exposure, lung-cancer screening will be a low-dose CT exam, with a radiation dose of around 1.5 mSv (millisieverts), equivalent to approximately half of the naturally occurring background radiation that a person receives living for one year at sea level. The exam does not require contrast.

All patients must be referred for the study by a physician. Please click here for scheduling information. It is important that a responsible healthcare provider manage followup care for patients with a positive finding.

Jo-Anne Shepard, MD

False positives

Although low-dose CT screening for lung cancer in high risk groups has been shown to have a definite benefit in saving lives, there is a negative aspect. "The number of false-positive studies is high," said Jo-Anne Shepard, MD, director of the Thoracic Imaging and Intervention division of the Department of Radiology. "For example, 40 percent of the screening CTs in the NLST revealed small indeterminate lung nodules that will require follow-up in order to determine if they grow, indicating a likely cancer."

Such results can lead to additional cost, radiation exposure, and patient anxiety. Larger nodules may require biopsy by means of an invasive procedure to establish the diagnosis and may lead to potential complications. Some of these nodules will be proven not to be cancer.

Active smokers undergoing screening CT should enter a smoking cessation program. Screening is not an alternative to smoking cessation.